Related by context. Frequent words. (Click for all words.) 70 emissions 68 pollution 66 air pollution 66 emission 66 carbon dioxide emissions 65 CO2 emissions 64 exhaust emissions 64 GHG emissions 64 nitrogen oxide emissions 63 GHGs 63 pollutants 63 NOx 62 pollutant 62 greenhouse gas emissions 62 nitrogen oxide 61 sulfur dioxide emissions 61 tailpipe emissions 61 CO2 emission 60 carbon dioxide CO2 emissions 60 nitrogen oxides 60 greenhouse gasses 60 greenhouse gases 59 Emissions 59 particulate matter 59 carbon emissions 58 greenhouse emissions 58 greenhouse gas emission 58 carbon emission 57 CO2 57 greenhouse gas 55 mercury emissions 55 carbon dioxide CO2 55 emission reductions 55 emission reduction 55 sulfur dioxide 54 reducing CO2 emissions 54 carbon dioxide 54 Emission 54 reduce carbon emissions 54 polluting 53 GHG 52 ozone pollution 50 smog 50 combustion 50 particulates 50 Clean Air 50 mercury pollution 49 VOCs 49 Pollution 49 ozone 49 nitrogen dioxide 48 volatile organic compounds 48 particulate 48 diesel engines 48 Air Pollution 48 reducing carbon emissions 48 diesel exhaust 48 global warming gases 47 heat trapping gases 47 cleaner fuels 47 soot 46 diesel 46 EPA 46 particle pollution 46 environmental impacts 46 acid rain 46 effluents 45 hazardous substances 45 polluter 45 carbon footprint 45 polluting industries 44 polluters 44 Air Quality 44 fossil fuel 44 cleaner burning 44 environmental 43 internal combustion engines 43 exhaust fumes 43 CARB 43 fossil fuels 43 pollute 43 hazardous wastes 43 Environmental Protection Agency 43 burning fossil fuels 43 toxic chemicals 42 environmentally damaging 42 VOC 42 carbon footprints 42 sulfur 42 environmentally friendly 42 gases 42 flue gas 42 Air Pollution Control 42 drivability 42 emitted 42 efficiency 42 atmospheric carbon dioxide 42 diesel engine 42 environmental friendliness 42 noise 41 ecological footprint